Fix Windows NVAPI loading the gfx1101 build on every other AMD GPU

0.1.5 shipped one d4r/zluda/nvapi64.dll (the gfx1101 build) for all
targets, and compat_nvapi_path() preferred it over d4r/nvapi/<arch>/.
Nothing on Windows ever set D4R_GPU_ARCH, so on any other GPU NVAPI
failed with "No selected gfx1101 device", NGX CUDA init failed, and
DLSS stayed unavailable (black frames, no OptiScaler upscaler section).

- Select the NVAPI per architecture; never fall back to a shared DLL
  in a multi-target folder, and report a missing build by name.

- The loader and runtime publish D4R_GPU_ARCH and D4R_GPU_LUID for the
  game's adapter, so NVAPI picks the right device with several GPUs.

- nvapi64.dll exports the target it was built for; the runtime refuses
  a mismatch, and the packager and d4r-check read the same marker.

- Release packaging no longer ships d4r/zluda/nvapi64.dll and rejects
  NVAPI builds for the wrong target, without a marker, or missing.

- Move target resolution, device matching and loader choice into
  gpu_selection.h; regression tests cover all 11 targets, bad or
  missing D4R_GPU_ARCH, mixed installs, multi-GPU and missing files.

- d4r-check: accept the FSR keys in the shipped d4r.ini.

tools/windows/gpu_environment.h

@@ -0,0 +1,20 @@
+#pragma once
+// Publishes the GPU the game renders on to the rest of the process. The NVAPI
+// compatibility DLL, the NGX core's CUDA initialization and any later shim
+// start from the environment, so the loader and the shim state the adapter's
+// real architecture and LUID before they load them.
+#include "gpu_selection.h"
+#include <windows.h>
+#include <cstdlib>
+
+namespace d4r::diag {
+// Updates the OS block (other DLLs, ZLUDA) and the CRT copy that getenv reads.
+inline void set_process_variable(const char* name, const std::string& value) {
+    SetEnvironmentVariableA(name, value.c_str());
+    _putenv_s(name, value.c_str());
+}
+inline void publish_selected_gpu(const std::string& architecture, const AdapterLuid* luid = nullptr) {
+    set_process_variable("D4R_GPU_ARCH", architecture);
+    if (luid) set_process_variable("D4R_GPU_LUID", format_luid(*luid));
+}
+}